Do you know from where your caffeine comes?

Americans drink five times as many soft drinks now than they did in the ‘50s. Author Murray Carpenter says the caffeine in these soft drinks is more likely than not man-made. (Justin Sullivan/Getty Images)

WASHINGTON — Caffeine is a central part of most Americans’ daily routines — from the morning coffee to the lunchtime soda to the post-dinner square of chocolate. And while the substance occurs naturally in more than 60 plants, not all of the caffeine consumed is natural. Much of it is synthesized in pharmaceutical plants overseas.